Family Bed Sizes: A Guide to Co-Sleeping Beds
"Family bed" means two things: the co-sleeping arrangement, and a specific mattress format — 120" wide, the width of two Queens side by side. If your household sleeps together on purpose, these are the four formats built for it, from smallest to largest. (All dimensions live in our oversized bed size guide.)
The co-sleeping lineup
| Format | Mattress | Sleeps comfortably | Minimum room |
|---|---|---|---|
| Alaskan King | 108" x 108" | 2 adults + 2 kids | 14' x 13' |
| Family Bed | 120" x 80" | 2 adults + 2–3 kids | 15' x 11' |
| Family Bed XL | 144" x 84" | 2 adults + 3–4 kids | 17' x 11' |
| Two Kings | 152" x 80" | the whole household | 18' x 11' |
Choosing between them
Alaskan King if you want depth as well as width — at nine feet long, nobody's feet reach the edge, and it's the best-known oversized format, which matters when you eventually shop for mattresses.
Family Bed if the room is wide but not deep. At standard King length it fits against an 11'-deep wall, and its ten feet of width give every child a lane that doesn't run through a parent.
Family Bed XL for the households where the kids never left and the dog was never asked to. Twelve feet wide — the largest single mattress we build before moving to split designs.
Two Kings solves the problem the others can't: different firmness preferences. Two full King mattresses sit side by side in one seamless frame, so one side can be plush and the other firm. It's also the easiest to source mattresses for — you're buying two standard Kings.
What a co-sleeping setup actually requires
- A frame built for the width: at 10–12 feet wide, center support is everything. Every Dovie Home frame is built to the exact format with solid wood slats — no sag in the middle lane.
- Bedding that exists: the real pain of a family bed is sheets. Ours are cut and sewn to order in linen, bamboo lyocell, and bamboo-linen for every format on this page.
- A room plan: check walkways and the delivery path first — our guide to fitting an oversized bed in your room covers both in ten minutes.
Frequently asked questions
What is the biggest bed size?
Of widely made formats, the Alaskan King (108" x 108") is the largest square. By width, the Family Bed XL (144") and Two Kings (152") are bigger still. Anything larger is a fully custom build — which we also do.
Is co-sleeping with a big bed safe?
For infants, follow your pediatrician's guidance — safe-sleep recommendations apply regardless of bed size. Oversized formats are most popular with families whose kids are past the infant stage, where the extra space is pure comfort.
Where do you find mattresses for these sizes?
Several specialty makers build to these formats — they're standardized enough that "Alaskan King mattress" or "Family Bed mattress" returns real options. Two Kings skips the problem entirely: two standard King mattresses.
Can we just push two beds together instead?
You can — two Queens make exactly a Family Bed's footprint — but the gap, the center ridge, and the bedding problem are real. We compared the DIY route against purpose-built frames in Two beds pushed together vs one oversized bed.